Defense lawyer Robert Watkins showed jurors a sweatshirt worn by his client, who was convicted of sexually assaulting a 9-year-old girl. (JAMES A. KIMBLE)

BRENTWOOD – A jury convicted a Massachusetts sex offender Thursday of sexually assaulting a 9-year-old girl while she was in the toy aisle of a Wal-Mart in Plaistow.

Jurors convicted Ronald Beausoleil, 34, of Haverhill, Mass., of aggravated felonious sexual assault and three other charges after roughly an hour and a half of deliberation in Rockingham County Superior Court.

Prosecutors argued that store security footage and the testimony of the young girl left no doubt that Beausoleil, a level-three sex offender in Massachusetts, was the assailant.

"This child might have only had four or five minutes alone with the defendant, but aren't those four or five minutes burned into her memory?" assistant county attorney Jennifer Haggar said during closing arguments. "She knew."

Beausoleil was arrested the night after the March 10 assault. A deputy sheriff spotted Beausoleil sitting in his truck in the store's parking lot.

Defense lawyer Robert Watkins argued that the lead detective in the case locked onto Beausoleil as the sole suspect after showing a single photograph to the girl while she was being treated at Lawrence General Hospital in Lawrence, Mass.

Watkins suggested the girl could have felt pressured to identify Beausoleil as her attacker since she was offered no other choices from a photo lineup.

"I would suggest to you it's a problem with adults, but it's a particular problem with children," Watkins said of a one-man photo lineup.

Beausoleil was also convicted of felonious sexual assault, accomplice to theft by unauthorized taking and driving after revocation.

Haggar argued that police were simply trying to identify a possible suspect when a detective showed the single photograph to the girl.

Police later released Beausoleil's photo to the public, asking for help in identifying him.

"This is a case of stranger danger," Haggar said. "Of course the police have an interest in sharing this with the public."

Judge N. William Delker revoked Beausoleil's bail after the verdict. A sentencing date is expected to be set within the next 60 days. Beausoleil faces a second trial in January for allegedly exposing himself to another young girl at a Wal-Mart in Salem on Sept. 19, 2011.

Prosecutors said that in the Plaistow case, Beausoleil was helping his girlfriend steal items from the store and searched for a girl to assault after his girlfriend left the store.

Moments after the assault, the girl went to the front of the store where she told a store manager about the incident, according to Haggar.

Jurors watched portions of video footage from Wal-Mart security cameras during Haggar's arguments. One segment showed a man identified as Beausoleil turning to notice the girl at the front of the store as she was leaving. He is shown walking by the store's exit again before putting his hood up and fleeing across the parking lot.

"He saw her as she walks out. He walks by. She is looking (at him)," Haggar said. "What does he do? He takes off running. He's gone."